KR20090129044A - Middle or large-sized battery pack case providing improved distribution uniformity in coolant flux - Google Patents

Abstract

PURPOSE: A middle or large-sized battery pack is provided to improve the uniformity of flow rate distribution, to remove the heat accumulated between unit cells, and to increase the performance and life span of the battery. CONSTITUTION: A middle or large-sized battery pack(70') in which a battery module laminated with rechargeable battery cell or battery module is mounted is positioned at the upper and lower sides in a opposition direction of a coolant inlet(10') and a coolant outlet(20') so that a coolant for cooling the unit cell(32) flows toward the opposition direction from one side of a battery module in a vertical direction of the cell lamination direction.

Description

Middle or Large-sized Battery Pack Case Providing Improved Distribution Uniformity in Coolant Flux}

The present invention relates to a medium-large battery pack case with improved distribution uniformity of refrigerant flow rate, and more particularly, a medium-large battery pack case equipped with a battery module in which a plurality of unit cells capable of charging and discharging are stacked. The discharge ports are located at the upper and lower portions of the pack case in opposite directions, and the refrigerant inlet and the refrigerant discharge portions are formed in the pack case, respectively, and the upper inner surface of the refrigerant inlet facing the upper end of the cell stack is opposite to the refrigerant inlet. It relates to a medium-large battery pack case made of a structure in which the slope of the inclined surface starting from the end increases in the direction of the refrigerant inlet relative to the upper end of the cell stack.

Recently, secondary batteries capable of charging and discharging have been widely used as energy sources of wireless mobile devices. In addition, the secondary battery has attracted attention as a power source for electric vehicles (EVs) and hybrid electric vehicles (HEVs), which are proposed as a way to solve the air pollution of conventional gasoline and diesel vehicles that use fossil fuels. have.

One or two or four battery cells are used for small mobile devices, whereas medium and large battery modules, which are electrically connected to a plurality of battery cells, are used in medium and large devices such as automobiles due to the necessity of high output capacity.

Since the medium-large battery module is preferably manufactured in a small size and weight, the rectangular battery, the pouch-type battery, etc., which can be charged with high integration and have a small weight to capacity, are mainly used as battery cells of the medium-large battery module. In particular, a pouch-type battery using an aluminum laminate sheet or the like as an exterior member has attracted much attention in recent years due to advantages such as low weight, low manufacturing cost, and easy form deformation.

In order for the medium-large battery module to provide the output and capacity required by a given device or device, it is necessary to electrically connect a plurality of battery cells in series and maintain a stable structure against external force.

In addition, since the battery cells constituting the medium-large battery module is composed of a secondary battery capable of charging and discharging, such a high output large capacity secondary battery generates a large amount of heat during the charging and discharging process. If this is not effectively removed, thermal buildup occurs and consequently accelerates the deterioration of the unit cell, and in some cases there is a risk of fire or explosion. Therefore, a vehicle battery pack that is a high output large capacity battery requires a cooling system for cooling the battery cells embedded therein.

On the other hand, in the medium-large battery pack composed of a plurality of battery cells, the performance degradation of some battery cells will cause the performance degradation of the entire battery pack. Since one of the main causes of such a performance non-uniformity is due to the cooling non-uniformity between the battery cells, there is a need for a structure capable of ensuring cooling uniformity during the flow of the refrigerant.

Among the medium and large battery packs according to the prior art, the refrigerant inlet and the refrigerant outlet are located at the upper and lower portions of the pack case in opposite directions, and the upper and lower surfaces of the flow space from the refrigerant inlet to the battery module are formed in parallel. You might use a pack case. However, in such a structure, the flow rate tends to be introduced into the flow path between the battery cells near the coolant outlet, and the flow rate decreases much in the flow path near the coolant inlet, making it difficult to uniformly cool the battery cells. .

In this regard, Korean Patent Application Publication Nos. 2006-0037600, 2006-0037601, and 2006-0037627 disclose that the battery cells are formed as the air guide surface formed to be inclined with respect to the opposite surfaces of the battery cells moves away from the refrigerant inlet. The medium-large battery pack is installed to be inclined downward so as to be closer to. Specifically, the air guide surface is formed at a constant inclination in a range of 15 to 45 degrees with respect to the opposite surface of the battery cells, thereby suppressing the phenomenon that the battery cell flow path refrigerant near the coolant discharge port is driven.

However, as confirmed by the inventors of the present application, despite the above structure, there is a problem that there is a significant temperature deviation between the battery cells, so that the desired level of temperature uniformity cannot be achieved.

Therefore, there is a high need for a technology that can fundamentally solve these problems.

The present invention aims to solve the problems of the prior art as described above and the technical problems that have been requested from the past.

After various experiments and in-depth studies on the medium-large battery pack case, the inventors of the present application have an upper inner surface of the coolant inlet so that the slope of the inclined surface starting at the opposite end of the coolant inlet is based on the upper end of the cell stack. Surprisingly, the flow rate of the coolant flowing in the flow path between the battery cells can be uniformly distributed, thereby effectively removing the heat accumulated between the battery cells and effectively reducing the performance of the battery. And it was confirmed that the lifetime can be greatly improved, and came to complete the present invention.

Accordingly, the medium-large battery pack case according to the present invention is a medium-large battery pack case in which a battery module capable of charging and discharging or a battery module in which a plurality of unit modules ('unit cells') are stacked is mounted, and a refrigerant for cooling unit cells. The coolant inlet and the coolant outlet are located at the top and bottom of the pack case in opposite directions so that the flow can flow from one side of the battery module to the opposite side in a direction perpendicular to the cell stacking direction, and a flow space from the coolant inlet to the battery module. ('Coolant inlet') and a flow space from the battery module to the coolant outlet ('coolant outlet') are respectively formed in the pack case, and the upper inner surface of the coolant inlet facing the upper end of the cell stack is the coolant inlet. The slope of the inclined surface starting at the opposite end of the structure increases in the direction of the coolant inlet with respect to the upper end of the cell stack It is made.

That is, in the medium-large battery pack case according to the present invention, the slope of the inclined surface starting at the opposite end (the end of the coolant outlet side) of the coolant inlet increases in the coolant inlet direction based on the top of the cell stack. Since the flow rate of the refrigerant flowing in the flow path between the unit cells (battery cell or unit module) can be made uniform, the heat generated during charging and discharging of the battery cells can be effectively removed by the uniform flow of the refrigerant. can do. As a result, it is possible to increase the cooling efficiency and to improve the operating performance of the unit cells.

Here, the "inclination increases" means that the inclined surface on the coolant inlet side is larger than the inclined surface located on the opposite end side of the coolant inlet port. Thus, the inclined surface may increase continuously or discontinuously in the direction of the refrigerant inlet. Here, 'discontinuously increasing' means that there may be a portion having a substantially 0 degree inclination at the border portion of the inclined surfaces. For example, a portion having an inclination of 0 degrees with respect to the upper end of the cell stack may be formed between the adjacent inclined surfaces.

The battery module mounted in the medium-large battery pack case according to the present invention is manufactured by stacking a plurality of unit cells with high density, and stacking adjacent unit cells at regular intervals so as to remove heat generated during charging and discharging. do. For example, the battery cells themselves are sequentially stacked while being spaced at a predetermined interval without a separate member, or in the case of battery cells having low mechanical rigidity, one or two or more combinations are embedded in a predetermined mounting member and the mounting members are mounted. By stacking a plurality of battery modules can be configured. The latter case is referred to as 'unit module' in the present invention.

When a plurality of unit modules are stacked to form a battery module, a flow path of a refrigerant is formed between the battery cells and / or between the unit modules so that heat accumulated between the stacked battery cells can be effectively removed. Made of structure.

The coolant inlet and the coolant outlet are flow spaces through which coolant can be introduced and discharged to effectively cool the generation of heat due to charge and discharge of the battery cells, and are formed at upper and lower portions of the pack case in opposite directions. In some cases. The coolant inlet and the coolant outlet may be formed at the bottom and top of the pack case, respectively.

The slope of the inclined surface of the upper inner surface of the refrigerant inlet may increase in the direction of the refrigerant inlet.

In one preferred example, the upper inner surface of the refrigerant inlet may be of a structure comprising two or more continuous inclined surface. That is, inclined surfaces starting from the opposite end of the coolant inlet and increasing in the direction of the coolant inlet may be formed on the upper inner surface of the coolant inlet.

According to an experiment conducted by the inventors of the present application, the upper inner surface of the refrigerant inlet portion has two or more inclined surface structures as compared with the case where the upper inner surface of the refrigerant inlet portion is parallel to the upper portion of the cell stack or has a single sloped slope structure. In the case of, it was confirmed that the performance was further improved by reducing the temperature variation of the unit cells.

In one specific example, the inclined surface of the upper inner surface may include a first inclined surface starting at an opposite end of the coolant inlet, and a second inclined surface having a larger slope than the first inclined surface between the first inclined surface and the coolant inlet.

In the above structure, the second inclined surface has an inclination increased by 20 to 500% with respect to the inclination of the first inclined surface in a range not exceeding 45 degrees with respect to the top surface of the cell stack, preferably inclined by 100 to 300%. It may be formed into a structure. Since the inclination of the second inclined surface does not exceed 45 degrees, an increase in the size of the pack case can be minimized. Further, since the inclination of the second inclined surface has a size that is at least 20% larger than the inclination of the first inclined surface, the uniformity of the refrigerant flow rate desired in the present invention can be ensured.

The first inclined surface may be formed in a structure having an inclination of 15 degrees or less with respect to the top surface of the battery cell stack, preferably may be formed to have an inclination of 2 to 7 degrees, more preferably 3 It may be made of a structure having a slope of 5 degrees.

In this case, the second inclined surface may have a structure having an inclination of 10 to 30 degrees with respect to the top surface of the cell stack in a range not greater than the inclination of the first inclined surface.

Meanwhile, the coolant inlet may have various inclinations according to the condition of the device in which the medium / large battery pack is mounted. For example, the coolant inlet may have a structure having an inclination equal to or less than that of the second inclined surface.

In some cases, when the coolant inlet is required to have a large angle due to the structural limitation of the device in which the battery pack is mounted, the coolant inlet may be configured to have a slope equal to or greater than the second inclined plane. Of course.

Experimentally confirmed by the inventors of the present application, when the inner surface of the upper end of the refrigerant inlet has a specific inclined structure as defined above, it was found that the influence of the angle of the refrigerant inlet on the flow uniformity of the refrigerant flow path is insignificant. Therefore, when the upper inner surface of the coolant inlet is made to have a specific inclined structure as in the present invention, there is an advantage that the angle of the coolant inlet can be freely determined according to the mounting conditions of the device.

In one preferred example, the refrigerant inlet may be made of a structure having a slope of 30 to 60 degrees with respect to the top surface of the cell stack in a range exceeding the slope of the second slope. Therefore, even when the angle of a large refrigerant inlet port is required by the condition of the device on which the battery pack is mounted, the above-described characteristic upper inner surface structure can effectively exhibit the desired cooling efficiency.

On the other hand, the opposite end of the refrigerant inlet may be formed in a structure spaced apart from the top surface of the cell stack to a height of 10% or less based on the height of the cell stack. This structure appropriately limits the amount of refrigerant reaching the opposite end of the refrigerant inlet, thereby further improving the uniform distribution effect of the refrigerant to the unit cells.

In this case, the opposite end of the coolant inlet may be a structure spaced apart from the top surface of the cell stack by about 1 to 10 mm, more preferably 1 to 3 mm spaced apart.

The battery cell is, as a secondary battery, a nickel hydride secondary battery, a lithium secondary battery, and the like, and the like. Among them, a lithium secondary battery having a high energy density and a high discharge voltage is particularly preferable. As the charge / discharge unit cell constituting the battery module, a rectangular battery and a pouch-type battery are preferable in terms of shape, and a pouch-type battery having a low manufacturing cost and a low weight is more preferable.

In addition, the battery pack case according to the present invention has a structure in which cooling efficiency is a particular problem, that is, the length of the battery pack case corresponding to the battery cell stacking direction is formed relatively longer than the length corresponding to the width direction of the battery cell More preferred in structure.

On the other hand, the refrigerant discharge portion may be formed to have a uniform height with respect to the lower end of the cell stack. That is, the lower inner surface of the coolant discharge unit facing the lower end of the battery cell stack may have a structure having a uniform height with the lower end of the battery cell stack. However, of course, some modifications may be made to increase the efficiency of refrigerant discharge.

In some cases, the coolant fan may be provided at the coolant inlet or the coolant outlet so that the coolant introduced from the coolant inlet may quickly and smoothly move to the coolant outlet and be discharged to the outside of the battery pack. May be additionally mounted. In such a structure, by the flow driving force of the refrigerant generated by the blowing fan, the refrigerant introduced through the narrow inlet reaches the battery cell far from the inlet at a high flow rate, so that the flow rate of the refrigerant is relatively uniform under the same conditions. The distribution effect is exerted.

The present invention also provides a medium-large battery pack having a structure in which a battery module is mounted on the medium-large battery pack case.

As used herein, the term “battery module” broadly refers to a structure of a battery system capable of providing high output and large capacity electricity by mechanically coupling two or more charge / discharge battery cells or unit modules and simultaneously electrically connecting them. Therefore, it includes both the case of configuring one device by itself, or part of a large device. For example, a large battery module may be configured by connecting a plurality of small battery modules, or a plurality of unit modules may be connected by connecting a small number of battery cells.

On the other hand, the structure of the unit module can be made in a variety of configurations, a preferred example will be described below.

The unit module has a structure in which plate-shaped battery cells having electrode terminals formed at upper and lower ends thereof are connected to each other in series, and two or more battery cells having a stacked structure in which the connecting portions of the electrode terminals are bent, and the Excluding the electrode terminal portion may be configured to include a high-strength cell cover coupled to surround the outer surface of the battery cells.

The plate-shaped battery cell is a battery cell having a thin thickness and a relatively wide width and length so as to minimize the overall size when it is charged for the configuration of the battery module. Such a preferable example may be a secondary battery having a structure in which an electrode assembly is embedded in a battery case of a laminate sheet including a resin layer and a metal layer, and electrode terminals protrude from upper and lower ends thereof, and specifically, a pouch type of an aluminum laminate sheet. It may be a structure in which the electrode assembly is built in the case. A secondary battery having such a structure may be referred to as a pouch type battery cell.

These battery cells can be configured as a unit module in a structure wrapped in a high-strength cell cover made of synthetic resin or metal in two or more units, the high-strength cell cover is charged and discharged while protecting the battery cell with low mechanical rigidity It prevents the sealing part of the battery cell from being separated by suppressing the change of repetitive expansion and contraction during the time. Therefore, it becomes possible to manufacture a medium-large battery module with more excellent safety ultimately.

The battery cells in the unit module or between the module modules are connected in series and / or in parallel, and in a preferred embodiment, the electrode terminals are arranged with the battery cells arranged longitudinally in series so that their electrode terminals are continuously adjacent to each other. After combining, the plurality of unit modules may be manufactured by folding the battery cells in two or more units so as to overlap each other and wrapping the cells in a predetermined unit by the cell cover.

Coupling of the electrode terminals may be implemented in various ways, such as welding, soldering, mechanical fastening, preferably by welding.

The plurality of battery cells or unit modules, in which electrode terminals are interconnected and filled with high density, may be vertically mounted in a vertically separated case coupled to a prefabricated fastening structure to form the rectangular battery module.

More specific details of a unit module and a rectangular battery module manufactured using a plurality of such unit modules are disclosed in Korean Patent Application Nos. 2006-45443 and 2006-45444, which are described by reference. Is incorporated into the contents of

The medium-large battery pack according to the present invention includes a plurality of battery cells in order to achieve high output and large capacity, and thus is particularly preferably used for power sources such as electric vehicles and hybrid electric vehicles in which high heat generated during charging and discharging is seriously raised in terms of safety. Can be.

Hereinafter, although described with reference to the drawings according to an embodiment of the present invention, this is for easier understanding of the present invention, the scope of the present invention is not limited thereto.

1 is a perspective view of a medium-large battery pack in which a battery module is mounted in a conventional medium-large battery pack case, and FIG. 2 is a vertical cross-sectional view of a medium-large battery pack in which a battery module is mounted in the medium-large battery pack case of FIG. 1. A schematic is shown.

Referring to these drawings, the medium-large battery pack 100 includes a battery module 32 in which a plurality of unit cells 30 are stacked and electrically connected, a pack case 70 in which the battery module 32 is mounted, and a refrigerant. The refrigerant inlet 40 is a flow space from the inlet 10 to the battery module 32 and the refrigerant outlet 50 is a flow space from the battery module 32 to the refrigerant outlet 20.

The coolant flowing from the coolant inlet 10 passes through the flow path 60 formed between the coolant inlet 40 and the unit cells 30 to cool the unit cells 30 and passes through the coolant discharge unit 50 to the coolant outlet. It is discharged to the outside through the (20).

The coolant inlet 40 is formed parallel to the stacking direction of the unit cells 30. In the above structure, the flow rate of the coolant inlet 40 tends to flow into the flow path between the unit cells near the coolant outlet 20. In the flow path between the unit cells 30 near the refrigerant inlet 10, the flow rate decreases a lot so that cooling between the unit cells 30 is uneven and the units near the refrigerant outlet 20 and the unit near the refrigerant inlet 10 are reduced. The cells will have a high temperature deviation. This phenomenon is because the temperature of the refrigerant inlet 10 increases as the flow rate is driven toward the refrigerant outlet 20.

3 is a vertical cross-sectional schematic diagram of a medium-large battery pack mounted with a battery module in a medium-large battery pack case according to another conventional art.

The medium-large battery pack 100a of FIG. 3 is substantially the same as the medium-large battery pack 100 of FIG. 1 in the unit cell 30, the battery module 32, the coolant discharge unit 50, the flow path 60, and the like. There is a difference in that the coolant inlet 10a and the coolant inlet 40a of the pack case 70a are inclined at a predetermined angle. That is, the upper inner surface 42a of the coolant inlet 40a forms an inclined surface inclined at a predetermined angle in the direction of the opposite end of the coolant inlet 10a.

This structure is compared with the medium-large battery pack 100a of FIG. 1, and the unit cell 30 adjacent to the refrigerant inlet 10a is known to have a relatively high cooling efficiency. However, as can be seen in FIG. 8, there is still a considerable difference in temperature in the structure of FIG. 3.

4 is a vertical cross-sectional schematic diagram of a medium-large battery pack mounted with a battery module in a battery pack case according to an embodiment of the present invention.

Referring to FIG. 4, the pack case 70 ′ has a shape in which the length corresponding to the stacking direction L of the unit cell 30 is relatively longer than the length corresponding to the width direction W of the unit cell 30. consist of. Further, in the direction perpendicular to the unit cell stacking direction L, the coolant inlet 10 'and the coolant outlet 20' are packed in opposite directions so that the coolant flows from one side of the battery module 32 to the opposite side. The upper and lower portions of the case 70 'are respectively formed.

A small flow path 60 through which the refrigerant moves may be formed between the unit cells 30, so that the coolant flowing from the coolant inlet 10 ′ moves through the flow path 60 to collect heat generated in the unit cell 30. After removal, the refrigerant is discharged through the outlet 20 '.

The difference between the pack case 70 'of FIG. 4 and the pack cases 70 and 70a disclosed in FIGS. 1 and 3 is that the pack case 70' of FIG. 4 has an upper inner surface of the coolant inlet 40 '. 42 'is inclined to the inclined surface which increases gradually. That is, the upper inner surface 42 ′ of the refrigerant inlet 40 ′ has a structure in which the slope of the inclined surface starting at the opposite end increases in the direction of the refrigerant inlet 10 ′ based on the upper end of the cell stack. A first slope (a) starting at the opposite end of (10 '), and a second slope (b) having a slope greater than the first slope (a) between the first slope (a) and the refrigerant inlet (10') It includes.

When the refrigerant is introduced from the refrigerant inlet 10 'and moves along the refrigerant inlet 40' of the first inclined plane a and the second inclined plane b, the flow cross-sectional area of the refrigerant is far from the refrigerant inlet 10 '. It is gradually reduced by the inclined surfaces (a, b) of the decreasing slope as it increases. In this process, the moving speed of the refrigerant gradually increases, but the flow rate of the refrigerant decreases, so that the amount of the refrigerant reaches the unit cells 30 located at a distance from the refrigerant inlet 10 'so that a uniform amount for each flow path 60 is achieved. Is introduced.

In order to increase the uniformity of the refrigerant, the first inclined surface (a) has an inclination of approximately 5 degrees with respect to the top surface of the cell stack, and the second inclined surface (b) is inclined to the inclination of the first inclined surface (a). It is formed on the upper inner surface 42 'of the coolant inlet portion 40' with an inclination of approximately 10 degrees increased by 200%.

Meanwhile, as illustrated in FIG. 4, the coolant inlet 10 ′ has a smaller slope than that of the second inclined surface b. Therefore, the refrigerant introduced through the refrigerant inlet 10 'passes through the point where the second inclined surface b starts and reaches the opposite end of the refrigerant inlet 10' as the flow rate becomes faster, so that the refrigerant inlet 10 ' The unit cells 30 and the unit cells 30 located at a distance from the refrigerant inlet may be uniformly cooled.

In addition, in the battery pack case 70 ', since the inclination of the coolant inlet 40' becomes smaller toward the opposite end of the coolant inlet 10 ', the slanted stepwise structure makes the coolant flow rate the coolant outlet ( 20 ') can be prevented from being squeezed toward, whereby the temperature of the unit cells adjacent to the refrigerant inlet 10' can be effectively prevented from rising.

5 is a vertical cross-sectional view showing a structure in which the opposite end of the coolant inlet 10 'is spaced apart from the top surface of the cell stack in the medium-large battery pack 200 manufactured with the structure of FIG.

Referring to FIG. 5, the opposite end of the coolant inlet 10 ′ is spaced at a height h of approximately 1 mm from the top surface of the cell stack, such that the second inclined surface b of the coolant inlet 40 ′. And only a limited amount of the refrigerant passing through the first inclined surface (a) reaches the opposite end of the refrigerant inlet (10 '), it is possible to prevent the unit cells 30 adjacent to the opposite end is overcooled.

In relation to the above description, FIG. 6 is a graph illustrating a result of measuring temperature change of battery cells in a medium-large battery pack manufactured by the structure of FIG. 2, and FIG. 7 is a medium-large battery pack manufactured by the structure of FIG. 4. The graph showing the result of measuring the temperature change of the unit module is shown.

Referring to FIG. 6 together with FIG. 2, FIG. 6 illustrates a temperature of battery cells stacked in a pack case from a battery cell adjacent to a coolant outlet to a battery cell located at a coolant inlet in a conventional pack case 70 structure. The results are shown. That is, battery cell number 1 denotes a battery cell adjacent to the refrigerant outlet, and battery cell number 43 denotes a battery cell adjacent to the refrigerant inlet.

The temperature measurement experiment was carried out under a condition that a predetermined load is applied to the battery cell and the ambient air temperature is room temperature. As a result, the relative temperature ratio of battery cell No. 1 adjacent to the opposite end of the refrigerant inlet was 48%, and the relative temperature ratio of battery cell No. 34 was 98%. The maximum relative temperature ratio was 98%. When the temperature of the battery cell exceeds a certain temperature, the life of the battery cell is drastically reduced, such a high temperature and temperature deviation as described above can not use the battery pack for a long time, there is a problem that also increases the possibility of explosion.

For reference, the relative temperature ratio of the battery cell is expressed here as a relative value comparable in relation to the experimental results of FIGS. 7 and 8 described later. In addition, the relative temperature ratio variation of the battery cells is interpreted as a temperature variation between the battery cells.

In comparison, FIG. 7 illustrates a result of measuring the temperature of the battery cells stacked in the pack case from the battery cell adjacent to the coolant outlet to the battery cell located at the coolant inlet in the pack case 70 ′ of FIG. 4.

Referring to FIG. 7 together with FIG. 4, under the same experimental conditions as in FIG. 6, the relative temperature ratio of the battery cell 1 is 61%, and the relative temperature ratio of the battery cell 31 is 65%. Can be reduced from 50% to 4%, and as a result, it can be seen that the temperature distribution uniformity of the refrigerant is greatly improved.

8 is a graph showing a result of measuring the temperature change of the unit module in the medium-large battery pack manufactured in the structure of FIG.

The experiment with respect to FIG. 8 was performed under the same conditions as in FIG. 7 except that the pack case 70a of FIG. 3 was used. Specifically, FIG. 8 illustrates an experimental result in a structure in which the upper inner surface 42a of the coolant inlet 40a is inclined at 30 degrees in the structure of FIG. 3.

As shown in FIG. 8, since the relative temperature ratio variation of the battery cells represents 5.5%, it can be seen that the temperature variation of the battery cells is relatively large when compared with the result of FIG. 7.

9 is a vertical cross-sectional schematic diagram of a medium-large battery pack mounted with a battery module in a battery pack case according to another embodiment of the present invention.

Referring to FIG. 9, the medium-large battery pack 200a of FIG. 4 has a slope of the refrigerant inlet 10 ′ which is greater than 10 degrees of inclination of the second inclined surface b. ), And other configurations are the same.

However, the uniform distribution of the coolant is hardly influenced by the inclination of the coolant inlet 10 ', which is shown in FIG. 10 showing the results of experiments varying the inclination of the coolant inlet 10' at various angles. You can check it. Specifically, FIG. 10 shows that the inclination of the first inclined plane a is 5 degrees, the inclination of the second inclined plane b is 10 degrees and the opposite end of the coolant inlet 10 'is 1 mm from the top surface of the cell stack. In the spaced apart condition, the experimental results are shown in the structures in which the angle of the refrigerant inlet 10 'is changed to 30 degrees, 45 degrees, and 60 degrees, respectively.

For reference, unlike FIG. 6 to FIG. 8, in FIG. 10, an experiment is performed under a condition in which an approximately 40% higher load is applied to each battery cell and the ambient temperature is lowered by about 5 degrees, and the temperature of the battery cell is measured. A graph showing one result.

As shown in Figure 10, it can be seen that there is little difference according to the change in the angle of the refrigerant inlet (10 '). Therefore, the inclination of the coolant inlet 10 'can be changed according to the structure of the device on which the battery pack is mounted while exhibiting an equal cooling efficiency.

As described above, the inner surface of the upper end of the coolant inlet of the medium-large battery pack case according to the present invention has a structure in which the slope of the inclined surface starting at the opposite end of the coolant inlet increases in the direction of the coolant inlet relative to the upper end of the cell stack. It is possible to improve the uniformity of flow rate distribution of the refrigerant, to effectively remove the heat accumulated between the unit cells, and ultimately to significantly improve the performance and life of the battery.

Those skilled in the art to which the present invention pertains will be able to perform various applications and modifications within the scope of the present invention based on the above contents.

1 is a perspective view of a medium-large battery pack mounted with a battery module in a conventional medium-large battery pack case;

Figure 2 is a vertical cross-sectional schematic diagram of the medium-large battery pack of Figure 1;

3 is a schematic vertical cross-sectional view of a medium-large battery pack mounted with a battery module in a medium-large battery pack case according to another prior art;

4 is a vertical cross-sectional schematic diagram of a medium-large battery pack mounted with a battery module in a battery pack case according to an embodiment of the present invention;

5 is a vertical cross-sectional view showing a structure in which the opposite end of the refrigerant inlet is spaced apart from the top surface of the cell stack in the medium-large battery pack of FIG. 4;

Figure 6 is a graph showing the result of measuring the temperature change of the battery cell in the medium-large battery pack of Figure 2;

7 is a graph illustrating a result of measuring a temperature change of a unit module in the medium-large battery pack of FIG. 4;

8 is a graph showing a result of measuring a temperature change of a unit module in a medium-large battery pack manufactured with the structure of FIG. 3;

9 is a vertical cross-sectional schematic diagram of a medium-large battery pack mounted with a battery module in a battery pack case according to another embodiment of the present invention;

FIG. 10 is a graph illustrating a result of measuring a temperature change of a unit module in medium and large battery packs in which a slope of a refrigerant inlet is changed to various sizes in the structure of FIG. 4.

Claims (17)

A battery pack or medium-large battery pack case in which a plurality of battery cells or unit modules ('unit cells') that are capable of charging and discharging are mounted. The refrigerant for cooling the unit cells is perpendicular to the cell stacking direction. The coolant inlet and the coolant outlet are located at the top and bottom of the pack case in opposite directions so as to flow from one side to the opposite side, and the flow space from the coolant inlet to the battery module ('coolant inlet') and the coolant outlet from the battery module. Flow spaces ('refrigerant outlets') are formed in the pack case, The upper inner surface of the coolant inlet facing the upper end of the cell stack has a structure in which the slope of the inclined surface starting at the opposite end of the coolant inlet increases in the direction of the coolant inlet relative to the upper end of the cell stack. Pack case. The medium and large battery pack case of claim 1, wherein the upper inner surface of the coolant inlet includes two or more continuous inclined surfaces. 2. The inclined surface of the upper inner surface includes a first inclined surface starting at an opposite end of the coolant inlet, and a second inclined surface having a larger slope than the first inclined surface between the first inclined surface and the coolant inlet. Medium and large battery pack case. The medium and large battery pack according to claim 3, wherein the second inclined surface has an inclination increased by 20 to 500% with respect to the inclination of the first inclined surface within a range not exceeding 45 degrees with respect to the top surface of the cell stack. case. The case of claim 3, wherein the first inclined surface has an inclination of 15 degrees or less based on the top surface of the cell stack. 6. The medium-large battery pack case of claim 5, wherein the first inclined surface has an inclination of 2 to 7 degrees with respect to the top surface of the cell stack. The medium and large battery pack case of claim 3, wherein the second inclined surface has an inclination of 10 to 30 degrees with respect to the top surface of the cell stack within a range exceeding the inclination of the first inclined surface. The medium and large battery pack case of claim 3, wherein the coolant inlet has an inclination equal to or less than that of the second inclined surface. The medium-large battery pack case of claim 3, wherein the coolant inlet has an inclination equal to or greater than that of the second inclined surface. The medium and large battery pack case of claim 9, wherein the coolant inlet has an inclination of about 30 to 60 degrees with respect to the top surface of the cell stack within a range exceeding an inclination of the second inclined surface. The medium-large battery pack case of claim 1, wherein the opposite ends of the coolant inlets are spaced apart from the top surface of the cell stack at a height of 10% or less based on the height of the cell stack. The medium-large battery pack case according to claim 11, wherein the opposite ends of the coolant inlets are spaced 1 to 10 mm from the top surface of the cell stack. The medium and large battery pack case according to claim 1, wherein the battery cell is a lithium secondary battery. The medium and large battery pack case of claim 1, wherein the coolant outlet has a uniform height with respect to a lower end of the cell stack. The medium and large battery pack case of claim 1, wherein a blower fan is further installed at the coolant inlet or the coolant outlet so that the coolant flowing from the coolant inlet passes through the battery module and moves to the coolant outlet. A medium-large battery pack having a structure in which a battery module is mounted in the medium-large battery pack case according to any one of claims 1 to 15. The medium and large battery pack of claim 16, wherein the battery pack is used as a power source for an electric vehicle or a hybrid electric vehicle.

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